As for an opening and closing device attached to an upper end of a fuel injection pipe, there is an opening and closing device shown in Patent Document 1. The opening and closing device includes a closing member turnably assembled relative to a main member, and such closing member closes an open portion from a back side of the fuel injection pipe by urging of a spring device. The closing member can contact a seal member provided on an upper face thereof with a seating face. In the opening and closing device of the Patent Document 1, the seal member has a Y shape in cross section, and this shape lowers a sealing performance when the back side of the fuel injection pipe, i.e. the inner side of a fuel tank has a pressure lower than that of the outside of the fuel tank. Also, this kind of seal member is made of a material having elasticity and easily swelling by fuel, so that in a case wherein the fuel is attached to the seal member, due to the aforementioned swelling, there causes a change at a position where the aforementioned seating face and seal member contact. This becomes a factor affecting a valve opening pressure of this kind of opening and closing device.